Whether it’s to reduce energy bills or to combat global warming, more people are turning to Web-based tools to track their energy consumption and associated carbon emissions. And companies like Carbonrally in Cambridge hope to turn that interest into a business.

“I built the company with the idea that the Internet can connect people with similar goals and interests,” said founder Jason Karas.

Carbonrally’s website, carbonrally.com, maps the energy-saving activities of users nationwide. The site feeds off of people’s tendency to be competitive by challenging them to take specific steps to conserve energy, Karas said.

For example, a recent challenge encouraged users to inflate automobile tires to the proper pressure. According to the site, about 1,600 people had done so, reducing their carbon emissions by 20.5 tons, “equal to turning off the electricity of 20 homes for about one month.”

In August, Carbonrally challenges began appearing in environmental and energy-related articles on Yahoo. In October, the Vermont Agency of Natural Resources teamed up with Carbonrally to launch the six-month Vermont School Carbon Challenge, an effort to get all of the state’s 391 public elementary, middle, and high schools to reduce carbon emissions by making simple changes.

Carbonrally is tracking every pound of carbon saved on its “rally machine,” and the results are tallied in real time online. The winning school will receive $5,000 for an energy-efficiency project.

Vermont Governor Jim Douglas kicked off the competition by pledging to take two of Carbonrally’s popular challenges: “Green Ham and Cheese,” aimed at getting people to use less paper and plastic when preparing homemade lunches, and the two-minute “Power Shower.”

According to Carbonrally, a typical lunch brought from home generates 65 pounds of garbage per child during a school year, and cutting a daily shower from eight to two minutes yields a carbon dioxide reduction of 15.3 pounds monthly.

Karas, who holds a master’s degree in environmental economics and business from Duke University, took a circuitous route to starting Carbonrally. He began his career doing nonprofit work at Cambridge’s Cultural Survival, a nonprofit organization that supports indigenous people worldwide, and spent a decade in telecommunications product management with such companies as GeoPartners Research Inc., Sapient Corp., and the European mobile operator Orange.

But in 2006, he said, he decided do something about climate change.

“I felt I could no longer sit on the sidelines,” Karas said. “I needed to get back to where my interests were and apply my training to the problem.”

Site traffic has doubled each quarter since Carbonrally was launched last November, with monthly visits averaging 15,000, Karas said. He self-funded the private company and is now raising capital to support its next stage of growth. He expects to turn a profit in another year.

Revenue comes from sponsors who underwrite challenges and position their brands and products within them. They include Soda Club Enterprises, an Israeli company that is the world’s largest manufacturer of home soda makers and has been reducing plastic bottle and soda can use; and Gazelle, a Boston company that buys and sells used tech equipment.

Matthew Gilbride, green-project leader for Friendship Hospital for Animals in Washington, D.C., said Carbonrally helped him to motivate his 115 employees to participate in a program that gauges the hospital’s energy use.

Other organizations that have become involved in tracking energy use online include:

Environmentalist and author Bill McKibben said Web-based environmental tools aren’t a substitute for political action. “But if they serve as a kind of gateway ‘drug’ into really doing something about the climate,” he said, “then I think they make sense.”

One thing that all sites like these are missing is the ability to make realistic comparisons across all the different actions / all the purchases / all the choices somebody makes — for example, everybody should change to CFL light bulbs, but that’s a drop in the bucket compared to simply flying less. How does going to get a coffee every morning compare to driving to and from work?

Unfortunately nobody yet knows a good way to do “personal energy accounting”, and its the subject of a lot of debate, and that’s why a site like WattzOn.com exists — its meant to help people understand the single choices every one makes and to put it in context, while also acknowledging and asking for help from the community to get the numbers better and more accurate.

Reducing carbon footprint is a good thing. But you must be realistic. Are the changings you want to make cost effective with today’s technology (and tax laws). Here are some calculators which look at actual $ savings :
Financial Calculators